1. Field of the Invention
The present invention relates to a tire information communication system comprising a tire-pressure detector mounted on a tire wheel for detecting tire pressure and transmitting a result of detection and a tire monitor provided in a vehicle body for obtaining the result of detection of tire pressure.
2. Description of the Related Art
Conventional tire information communication systems of the above-mentioned type comprise a tire-pressure detector and a tire monitor. Radio communication is carried out between the tire-pressure detecting device and the tire monitor so that a result of detection of tire pressure by the tire-pressure detector is transmitted to the tire monitor. JP-A-2005-119370 discloses one of the above-described tire information communication systems. The tire-pressure detector includes a loop antenna for radio communication and is fixed on a tire wheel. The tire monitor also includes a loop antenna and is disposed inside a dashboard of the vehicle body.
However, the above-described conventional system is susceptible to a null point where the communication sensitivity thereof is extremely lowered due to difference in a rotational position of a tire. As a result, communication performed by the system becomes unstable. Furthermore, the communication sensitivity is generally low other than the null point. Power consumption is increased in order to compensate for the low communication sensitivity.